Grey cast iron containing graphite in spherulitic form



Patented Aug. 5, 1952 GREY CAST IRON CONTAINING GRAPHITE IN SPHERULITIC FOR-M- .Iames Fernando Jordan, Huntington Park, Calif.

No Drawing. Application June 2, 1951, Serial No. 229,660

1 Claim. 1

My invention relates to the manufacture of nodular iron.

During the course of certain experiments regarding methods of adding magnesium to molten iron, I noticed that certain of the resulting samples of nodular iron were tougher than I had anticipated. Analysis of these tough samples for the conventional elements showed nothing that seemed to explain the toughness. While it was noted that most of the tough samples were made with the addition agent, magnesium nitride, certain samples of iron made with magnesiummicizel and magnesium-silicon also exhibited this tough characteristic.

It then occurred to me that the nitrogen content of the metal might have a bearing on the toughness of nodular iron, and analysis of the various samples for nitrogen showed that the tough samples all contained a relatively high percentage of nitrogen.

As I say, this desirabl tough characteristic appeared in only a few of the samples made with magnesium-nickel and magnesium-silicon, and it appeared in all of the samples made with magnesium nitride. The question then arose regarding the possibility of assuring the toughness in the magnesium-nickel/magnesium-silicon type of irons by lifting the nitrogen content of such irons.

I then made a series of nodular irons employing magnesium-nickel and magnesium-silicon as addition agents. After having taken samples of each batch of molten metal, I lifted the nitrogen content of th molten metal, whereupon I took an additional series of samples. In comparing the low-nitrogen with the high-nitrogen samples, I

found that the toughness of the metal was always increased when nitrogen was added.

I found that nitrogen values below 0.010% seemed to contribute little towards improving the toughness of the metal, and I found that nitrogen values in the range between 0.010 and 0.20%

substantially improved the toughness of the metal.

The magnesium and nitrogen may be added to the molten metal with the addition agents: magnesium nitride, magnesium cyanide, or magnesium cyanamide. Or the magnesium may be added separately by means of the addition agents: magnesium-nickel, magnesium-copper, magnesiumsilicon, or magnesium, and the nitrogen may be added by means of calcium cyanamide, air, nitrogen, or other compounds of nitrogen. Other addition agents for adding magnesium and/ or nitrogen will occur to those skilled in the art.

While I have herein employed the widely-accepted practice of referring to magnesium-bearing iron as nodular iron, the expression nodular iron does not accurately describe this new material, for it is not the iron that is nodular. Others have described this material as grey cast iron having uncombined carbon in a spherulitic form, and, in view of the fact that this more concisely describes the material, I employ it in my claim to identify and describe the nodular iron of my specification.

Having now described several forms of my in vention, I wish it to be understood that my invention is not to be limited to the specific forms or arrangement of steps hereinbefore disclosed, ex-

cept insofar as such limitations are specified in the appended claim.

I claim as my invention:

Magnesium-bearing grey cast iron having uncombined carbon in sp-herulitic form and containing 0.0l00.20% nitrogen.

JAMES FERNANDO JORDAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,335,370 Ellis Mar. 30, 1920 1,920,934 Keen Aug. 1, 1933 

